Thanks for the explanation on “Western”. I now also found Available Language Modules. Thanks for telling me how this section is actually named…
In that section I do not see “German”. So it does not seem to be installed, but I can choose it in Tools → Language → For Selection/Paragraph/All Text. That clearly is a bug I will report.
So in that sectionAvailable Language Modules I do not see “German” so I click on Edit. In the new popup box there is no button “New” or "Installed, but on the bottom there is a link Get more dictionaries online. So I click on that.
In the new window I search for “German” but I see that a “German Spellchecker” is already installed.
I also can select “German (Germany)” from the dropdown, but there is no button “Add”. Not sure what this dropdown box is for. Also the click on “Reset” does not do anything visible.
That brings me back to my original question: How can I spell check a text in German?